Process for preparing a silver catalyst

Abstract

A supported silver catalyst for oxidation of ethylene to ethylene oxide is prepared by impregnation of the support, activation, and solvent washing, with each step being carried out at a relatively low temperature. Silver so deposited has an average particle diameter of about 0.5-0.7 microns and is capable of being promoted by post-deposition of alkali metals such as cesium, rubidium, and potassium.

What is claimed is: 
     
       1. A process for preparing a catalyst useful in the oxidation by molecular oxygen of ethylene to ethylene oxide comprising: (a) impregnating a support with a solution of a silver salt selected from the group consisting of silver acetate, silver benzoate, silver oxalate, silver lactate, silver malonate, silver succinate, silver glutarate, and silver maleate and comprising at least one non-nitrogenous reducing agent selected from the group consisting of alcohols, polyols, and keto alcohols at a temperature at or below 110° C.;   (b) activating and drying said impregnated support of (a) at a temperature not below 85° C. or in excess of 200° C. for a sufficient time to permit substantially all of the silver in the impregnated solution to be deposited on said support and leaving decomposable residues on said support;   (c) removing at least 85% of said residues of (b) from said activated support (b) by washing said support with a solvent;   (d) thereafter post-impregnating the catalyst of (c) with a solution of a compound of one or more alkali metals selected from the group consisting of cesium, rubidium, and potassium and thereafter drying said post-impregnated catalyst.